jQuery Pocket Reference

Advanced Event Handler Registration

We’ve seen that jQuery defines quite a few simple methods for registering event handlers. Each of these simply invokes the single, more complex method bind() to bind a handler for a named event type to each of the elements in the jQuery object. Using bind() directly allows you to use advanced event registration features that are not available through the simpler methods.^[2]

In its simplest form, bind() expects an event type string as its first argument and an event handler function as its second. The simple event registration methods use this form of bind(). The call $('p').click(f), for example, is equivalent to:

$('p').bind('click', f);

bind() can also be invoked with three arguments. In this form, the event type is the first argument and the handler function is the third. You can pass any value between those two and jQuery will set the data property of the Event object to the value you specify before it invokes the handler. It is sometimes useful to pass additional data to your handlers in this way without having to use closures.

There are other advanced features of bind() as well. If the first argument is a space-separated list of event types, the handler function will be registered for each of the named event types. The call $('a').hover(f) (see Simple Event Handler Registration), for example, is the same as:

$('a').bind('mouseenter mouseleave', f);

Another important feature of bind() is that it allows you to specify a namespace (or namespaces) ...